Bacterial meningitis is a life-threatening disease. In adults, Streptoccocus pneumoniae and Neisseria meningitidis are the predominant agents, with an overall fatality rate of approximately 30% and 10%, respectively. Viral meningitis and encephalitis is also life-threatening. Although the most common causative agent (enterovirus) presents relatively rarely with neurological complications, Herpes simplex-1 (HSV-1) meningoencephalitis has >70% mortality if untreated. Early treatment improves prognosis in all forms of meningitis and encephalitis, and therefore early diagnosis is vital.
Diagnosis and treatment remain a major challenge, mainly due to the often difficult distinction of acute bacterial meningitis from viral CNS infection or neuroborreloiosis at presentation. Conventional clinical and laboratory variables such as White Blood Cell (WBC) count, or levels of lactate, protein, glucose, or plasma C-reactive protein (CRP), typically measured in the cerebrospinal fluid (CSF), are often not discriminative enough in the early phase of the disease. Final diagnosis requires a blood or CSF culture positive for bacterial infection, or positive identification of bacteria in the CSF following, for example, Gram-staining. A positive result in one of these assays is generally taken to be proof of a bacterial origin is proven and further tests are not necessary. However, these tests have an overall sensitivity of only 60% to 90%. Also, many patients receive antibiotics prior to lumbar puncture, reducing the chance of a definitive result from CSF culture or Gram-staining. Culture in particular is also time-consuming, leading to a delay in diagnosis. As a result of these factors, patients suspected of having meningitis are typically given a default treatment of broad-spectrum antibiotics and antiviral therapy, pending final diagnosis.
A reliable biological or clinical marker to determine as early as possible whether or not an individual has bacterial meningitis is needed.